1. Field of the Invention
The present invention relates to a flat motor used as a silent alarm source in a mobile communications apparatus, and more particularly, to a non-circular, flat motor in which terminal portions are installed in dead space.
2. Description of the Related Art
Vibration motors using a centrifugal force of an eccentric body are now used as a silent alarming source in mobile communications apparatuses. Also, there is a flat coreless motor having a pinion gear at an output shaft which is used for transferring a pickup for detecting signals of a disc medium.
A conventional cylinder type vibration motor having a diameter of 4 mm is currently being widely used. However, since the vibration motor is mounted using a holder, the actual diameter thereof becomes 5 mm, which has not kept pace with the ongoing trend in miniaturizing portable apparatus. Furthermore, the vibration motor is a narrow cylinder so that sufficient space in a radial direction for an eccentric weight installed at an output shaft cannot be secured, resulting in weak vibrations. In comparison, a flat motor having a thickness of 3 mm can be easily obtained. Also, a large space in a radial direction can be obtained. The conventional flat vibration motor is shown in FIG. 12.
Referring to FIG. 12, a bracket B is formed of a magnetic body which is also used as a yoke. A thin disc magnet D is located on the bracket B and a shaft holder Ba is formed by raising a central portion of the bracket B. A shaft S is pressed into the shaft holder Ba and fixed thereto. An eccentric rotor R is rotatably installed at the shaft S to face the magnet D with an axial gap. The bracket B is covered by a thin case K.
A flat commutator C is formed of a printed circuit board and installed at the eccentric rotor R. A pair of brushes Br for providing electric power to the flat commutator C by slide-contacting the brushes Br are soldered to a thin flexible sheet FS. The flexible sheet FS, which extends outward between the magnet D and the bracket B, serves as a feeder terminal.
With a recent trend in small and light mobile communication apparatus, electric parts mounted thereon must be small and light and there is a need for parts that can be reflow soldered, a type of soldering used in automation of an assembly process. However, in the case of an apparatus using an electric part having a magnet, such as the flat motor, the magnet thermally deteriorates due to the high temperature during the process of reflow soldering. Also, it is difficult to hold the conventional motor, which is circular when viewed in a plane, with a transferring apparatus and the flexible sheet is very likely to be damaged when it is automatically mounted.
Also, in a method of installing the brushes Br at the thin flexible sheet FS by soldering, a displacement due to the spring force of the brushes Br when they slide-contact the flexible sheet FS needs to be prevented, so that the entire process becomes complicated. Also, the shaft itself becomes very small so that the manufacturing price of the shaft increases or the process of inserting the shaft is complicated.
To solve the above problems, it is an object of the present invention to provide a non-circular flat vibration motor which does not adopt a flexible sheet type feeder terminal, has a non-circular shape when viewed in a plane so as to be easily held by a transferring apparatus and automatically mounted, and has feeder terminals which are easily soldered, and a manufacturing method thereof.
Also, it is another object of the present invention to provide a non-circular flat vibration motor which uses a housing member instead of the shaft and can be simultaneously operated without a the flexible sheet and can be reflow soldered, and a manufacturing method thereof.
Also, it is yet another object of the present invention to provide a light, non-circular, flat vibration motor.
Accordingly, to achieve the above objects, there is provided a non-circular flat motor comprising a rotor, a housing formed to be non-circular when viewed in a plane which supports the rotor to be capable of rotating and simultaneously at least a part of side surfaces has a flat surface, and a plurality of feeder terminals arranged at an angled corner at the side surface of the housing which is formed by electrically insulating at least one terminal of high electric potential from other portions adjacent thereto.
It is preferred in the present invention that the armature coil is arranged at a stator base functioning as part of the housing and simultaneously a magnet facing the armature coil is arranged at the rotor.
Also, it is preferred in the present invention that the housing is substantially rectangular and at least some of the feeder terminals are formed not to protrude outward over a corner of the rectangle as an angled portion for installation.
Also, it is preferred in the present invention that the motor further comprises a flat magnet, a bracket as part of the housing where the magnet is arranged, a brush incorporated with the feeder terminals via a gap between the bracket and the magnet, wherein the rotor receives electric power from the brush and simultaneously faces the flat magnet via a gap in an axial direction.
Also, it is preferred in the present invention that a base end portion of the brush is formed as part of the feeder terminal as it is.
Also, it is preferred in the present invention that the housing is substantially rectangular and at least some of the feeder terminals are formed not to protrude outward over a corner of the rectangle as an installation portion.
Also, to achieve the above objects, there is provided a non-circular flat motor comprising a rotor, a housing including a stator base having a shaft for supporting the rotor provided at the center thereof and having a non-circular shape, part of the housing being formed of resin, and at least two feeder terminals arranged at an angled corner at the side surface of the housing which is formed by electrically insulating at least one terminal of high electric potential from other portions adjacent thereto.
It is preferred in the present invention that the shaft is installed by erecting a shaft core from part of the housing constituting a stator and coating the shaft core with resin to form a resin coated, fixed shaft, and the rotor is rotatably installed from a tip of the resin coated, fixed shaft and the tip of the shaft is inserted in a concave portion installed at the other portion of the housing.
Also, it is preferred in the present invention that the motor further comprises a yoke plate formed of a magnetic body and having the shaft core integrally protruding from the center thereof, constituting part of the housing, a brushless recess portion formed at the yoke plate to insulate the brush at least at one side, a resin bracket portion which includes a resin coated, fixed shaft made by incorporating in the resin bracket portion at least part of the yoke plate and coating the shaft core with resin, a rotor including a commutator and an armature coil having one end portion connected to the commutator and rotatably arranged at the resin coated, fixed shaft to face a magnet via a gap, a pair of brushes having a free end in sliding contact with the commutator and fixed such that at least two surfaces can expose base ends of the resin bracket portion through the brush recess portion, the magnet arranged at least at the yoke portion of the resin bracket portion after the brushes are arranged, and a case accommodating the rotor and installed at the resin bracket by inserting a tip of the resin coated, fixed shaft in a concave portion formed at the center of the case, at least a magnetic path portion of the magnet being formed of a magnetic body.
Also, it is preferred in the present invention that the magnet is separated from the yoke plate by a small gap to enable reflow soldering.
Also, it is preferred in the present invention that the yoke plate is separated from the case except for a combined portion.
Also, it is preferred in the present invention that a portion for reflow soldering is not close to the combined portion.
Also, it is preferred in the present invention that the resin of the resin coated, fixed shaft includes potassium titanate whisker and has an anti-thermal feature bearing a thermal deformation temperature of over 200xc2x0 C. (18.5 kgf/cm2) and a slippery feature.
Also, to achieve the above objects, there is provided a non-circular flat brushless motor comprising a metal plate incorporating a shaft support portion at the center thereof, forming part of a housing, a fixed shaft supported by the shaft support portion, a rotor rotatably installed at the fixed shaft from a tip thereof, and a stator formed of a plurality of armature coils arranged around the fixed shaft to drive the rotor, in which the other part of the housing supports a tip of the fixed shaft.
It is preferred in the present invention that the fixed shaft has a shaft core cut from a metal plate and the shaft core is coated with resin.
Also, it is preferred in the present invention that a pinion is incorporated in the rotor.
Also, it is preferred in the present invention that the rotor is formed to be eccentric to generate vibrations during rotation.
Also, to achieve the above objects, there is provided a method of manufacturing a brush type non-circular flat motor comprising the steps of press-pressing a lead frame having a plurality of yoke plates continuously installed at a predetermined pitch by a connection portion, inserting the continuously installed yoke plates in an injection mold and integrally molding a resin bracket, detaching at least the connection portion of the yoke plates among the respective connection portions, installing the rotor at a fixed shaft to be capable of rotating, and installing the case.
It is preferred in the present invention that the method further comprises steps of fixing brushes to a resin bracket by a spot welding method, the brushes being formed by continuously installing via a plurality of connection portions at the same pitch as the predetermined pitch, and installing a magnet at the yoke plate.